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W; A. BEIGE.

PHOTOGRAPHIC TESTING-PLATE FOR CAMERAS.

Patented Sept. 12, 1876 w tness-semen, on LONDON, nnesnnn.

ncsnovsusnrm snotoeenemorssrineeieres sonca m-suser Specification forming part of Letters Patent Nmjflfilflllili, dated September 12, 18%;. application filed I May 1, ism.

To all whom it may concern:

Be it known that I, WILLIAM A. BRIOE, of London, England, have invented a new and Improved Photographic Testing-Plate or Actinometer, of which the following is a specifleation:

In the accompanying drawing, Figure 1 represents a front view of my improved photographic testing-plate or actinometer; Fig. 2, a vertical transverse section on the line a: m, Fig. 1; and Fig. 3, a horizontal section of the same on line 0 c, Fig. 1.

Similar letters of reference indicate some spoudi-ng parts.

The object of my invention is to furnish photographers an improved testing-plate, that may be readily applied to the camera, for the purpose of enabling them, in a very convenlent and reliable manner, to determine with considerable certainty the quality ol' the chemicals employed, the quick or slow working of. the lens, and todeline whether the presence of fog or want of clearness in the picture is attributable to-impurities of the chemicals,

alkalinity of the bath, diffused light, over-exposure to light, or to other causes.

The invention consists of a frame with a slidingglass plate, to which are applied fixed pieces of transparent material superposed in layers of one, two, three, and more, in regular succession, to produce-a greater or less obstacle to the passage ofthe light.

In the drawing, 'A represents awooden frame, adapted to any size of camera, and at- V tached by means of hinges and hooks or screws in'such a manner that it may he placed into 'positioe for use or moved out of the Way to allow the taking of the photographs in the usual manner. into grooves of the wooden frames is let loosely, so as to be adjustable to diiferent heights, a glass plate, B, that is provided on one face or side with a series of fixed plates or sheets, 0, of transparent m'aterial that l y the superposition of two, three, or more thicknesses, greater or less resistance is produced to the passage of the light, The transparent sheets may be employed in any suitable manner, in longitudinal orvlateral rectioh, and pr'eferlably so that the center part which are arranged in such a manner of the glass plate is left free, while the adjoin, lug parts are covered with one layer of transparent material, the next adjoining sections is set up between the lens and the sensitized plate, and the picture is then' taken in the usual manner, The result is a'picture which produces the light shade or shadow of the object to be photographed with the cheinioals and lehs, and with light of more or less the same actinic quality, intended tobc used for the picture to be taken. i

When the picture is developcd ontheplate,

wefiud that the whole picture is"visihle, -but that it is divided into sections of unequal intensity, being more or less distinct according as the light had to pass through one or.more

layers The absence of fog at the place where the light had' to pass through several layers or sheetsof transparent material-indicates that the chemicals are pure, that there is no diffused light, and that the nitrate bath is of proper acidity. If at that section details of the pictureare clearly developed, we can conclude that .t 6 exposure has been suflici'ent with the lens light, and chemicalsuse'd. The second section of the testing-plate, where the light had to pass through a les number of layers, gives more or less the same information, but indicates more clearly whether the exposure hasheen adapted to existing conditions or not. 'ihene'st section indicates, if properlydeveloped, what time, chemicals, 8m, areto be used for the picture to be taken, WllliB- the middle or uncovered section indicates by the evident over exposure that the lens is good an rapldtin action, that the chemicals are in good condition, and that the light is sulficient in actiuic power to produce good pictures with rapid exposure.

The difi'erent sections ot' the testing-plate admit thus, in a quick. and reliable manner, a conclusion as to the quality of the chenilcals, lens, and light, and furnishes thereby to the photographer a cheap and simple device of adapting himself quickly and successfully uircumatances, anti produce good pictures without Resins; the has; mum of the fight by a failure of the chemical apgaratns or erronewn th of ex osure.

maxing thus descnbeu my ,nvenfamn, A 01mm new and. desire to secure by Letters Pateat-- The photographic testing-plate or actiuome- 1m: herein described, consisting of the frame A and the s'iiding glass plate B, fliviflefi sections G by sheets 01- layers in trump 2x1; material, the device being ad apted. far zmzmcilmentto a photographic camera, and. use in the manner herein set; forth "WILLIAM ALEXANDER Wiinasses:

{BI-MS H. UP'iON 1-11 A. UPTQN, 

